The invention relates to a method and a device for controlling the movement of a wiper blade over a surface.
In order to rid a windscreen on a motor vehicle of contaminants and moisture, a wiper blade is moved across the screen in a reciprocal motion. For this purpose the wiper blade is usually mounted on a wiper arm, which is driven about a wiper shaft in an oscillatory motion. The wiper blade comprises a wiper lip, which rests on the windscreen and is pulled across it. The wiper lip is pulled by the wiper blade, so that for each change of direction of the wiper blade or the wiper arm, the wiper lip changes the side with which it is resting on the windscreen.
In order to avoid the wiper lip becoming brittle on one side, the wiper blade is moved prior to the wiper system stopping, so that the wiper lip is brought into a predetermined placement position. The placement position can, for example, be changed periodically, either under timer control or after a predetermined number of placements of the wiper lip in the same placement position. The placement positions of the wiper blade on the windscreen are always located in a lower area on the windscreen.
Investigations have shown that with dry or very dirty windscreens, a movement carried out by the wiper arm in order to bring the wiper lip into the predetermined placement position can cause the wiper arm to strike a boundary in the lowest area of the windscreen when starting from the placement position, because of elastic tensing of drive elements of the wiper arm. A noise effect connected to this can be perceived as unpleasant by a person near the wiper blade. Moreover, the service life of the wiper blade can be reduced by the impacts.